1. Field of the Invention
The present invention relates to an ink cartridge-attaching device capable of detecting degradation of an optical sensor which detects a cartridge attached to a cartridge attachment section.
2. Description of the Related Art
Conventionally, there are widely known ink-jet recording apparatuses each of which records an image and/or a letter on a recording paper by jetting ink from a recording head onto the recording paper. A cartridge storing the ink can be attached to the recording apparatus, and the ink supplied from the cartridge is jetted from the recording head. In a case that a remaining amount of the ink remaining in the cartridge (ink remaining amount) becomes relatively small, the cartridge is removed from the recording apparatus and a new cartridge filled with the ink is attached to the recording apparatus, whereby image recording can be continued to be performed.
Among the ink-jet recording apparatuses, there is an ink-jet recording apparatus including an optical sensor which detects the ink remaining amount in a cartridge attached to the recording apparatus (see, for example, United States Patent Application Publication No. 2007/0070148 corresponding to Japanese Patent Application Laid-open No. 2007-196650). The optical sensor is provided with a light-emitter and a light-receiver, wherein the light emitter emits light toward a portion to be detected (detection-objective portion) of a cartridge attached to a predetermined cartridge attachment section and the light-receiver receives the light via the detection-objective portion; and based on a state of the light reception by the light-receiver, the information about the ink remaining amount in the cartridge can be detected. More specifically, the detection-objective portion of the cartridge shields the light when the ink remaining amount is not less than a predetermined amount, whereas the detection-objective portion allows the light pass therethrough when the ink remaining amount is less than the predetermined amount. Further, the optical sensor is constructed so as to output a signal indicating that the ink remaining amount is less than the predetermined value when the light from the light-emitter passes through the detection-objective portion and the light having a predetermined brightness or luminance is received by the light-receiver in a state that the cartridge is attached.
Generally, in the optical sensor, a light-emitting diode and a photo diode are used as a light-emitting element and a light-receiving element, respectively. In particular, the light-emitting diode has a characteristic that the light-emitting diode is deteriorated as the operating time passes such that illuminance or brightness of the light-emitting diode during the operation is lowered. Further, in order to detect the ink remaining amount as described above, the optical sensor needs to be operated for a long period of time in a state that the cartridge is attached. Therefore, it is preferable that the degradation state of the optical sensor can be grasped in the state that the cartridge is attached. However, in the cartridge as described above having the detection-objective portion which shields the light from the light-emitter when the ink remaining amount is not less than the predetermined amount, it is difficult to correctly determine whether or not a state that the light-receiver does not receive a light having a predetermined luminance is due to the ink remaining amount being not less than the predetermined amount or due to the lowering of illuminance caused by the degradation of the light-emitter.